shop floor heat help please

Harvey Ramer

The boiler should have a BTU rating. If you can't find it you'll have to contact the manufacturer.

jtpfarm

It's rated at 100,000. I wouldn't guess 85% efficient.

Harvey Ramer

Typically, solid fuel boilers are rated by their output @ a certain moisture content in the fuel.

So you are able to keep a 53° indoor temp after a week of zero degree weather. If you would like the floor to be able to carry the entire load, you definitely need a bigger boiler. There is however a very real possibility that your downward heat loss is what's killing the boiler. Therefore, with supplemental heat, such as the Modine, that is not exposed to the downward heat loss, it is likely that the current boiler can meet the load.

Could you give us a rough drawing of the shop that shows all the windows and doors. Also is the corn boiler inside the shop or not?

Include;
Building dimensions
Ceiling height
SF of doors and their R-values
SF of windows and their R-values
Wall buildup construction including the R-values of the insulation in the cavity. Same with the ceiling.
Slab thickness
Perimeter insulation under slab R-value and also dimensions. Does it come in 4', 6', ect...
Edge insulation R-value, if any? This would be between the edge of the slab and the outer wall.

Desired indoor temp.
What is the closest major city?

jtpfarm

Here is some data I collected.

First. I did some checking and my boiler with the primary loop hold 19.2 gallons. After running for an hour I can raise the temperature 3.6 degrees in 1 minute. If I understand BTU correctly, that is only roughly 30,000 BTU. Can this be right?

Also in response to your post above:

-Boiler is in a separate insulated room from the shop

-The shop is a block wall round roof barn gutted with the ceiling raised.

-Dimensions are 60x40. 19 foot ceiling.

-24x18 door at R12 on the south wall. (40 foot)

-4- 36 x 24 windows. No idea on the r value.

-Bottom 9 feet of the building is 2 layers of clay block with a 2 inch air gap between them. Inside of that there is R12 fiberglass.
Above that is R19 batts plus 4 inches of blow in fiberglass to take up an air gap.

-Also the north wall is exposed to cold storage, not the elements.

-Ceiling is 30 inches of blow in fiberglass.

-Perimeter insulation comes in 4 feet and is R9

-Edge consists of an outer footing that is 7 feet deep, then inside that is R9 the thickness of my slab.

The slab is 4 inches thick on the outside and gradually increasing to 7 inches in the middle.

- I would be happy with 60 degrees.

- I am about half way between Minneapolis and Souix Falls.

I can draw a picture If needed.

Harvey Ramer

"I can draw a picture If needed."

Could you? Maybe with notations pointing out the above info and how it applies. Windows double pane or single pane.

jtpfarm

The windows consist of 2 single pane with a 14 inch air gap between them. (one on the outside of building, on inside)

Here are my drawings.

Harvey Ramer

jtpfarm said:

First. I did some checking and my boiler with the primary loop hold 19.2 gallons. After running for an hour I can raise the temperature 3.6 degrees in 1 minute. If I understand BTU correctly, that is only roughly 30,000 BTU. Can this be right?

Is that with only the boiler running and the heat going to the floor turned off?

By the way, I'm going to run a load on the building, with the data you gave me. I'll slip it in as soon as I have time.

jtpfarm

Yes, that is just the boiler running with no load.

Ironman

jtpfarm said:

It's rated at 100,000. I wouldn't guess 85% efficient.

I'm late for this party, but a couple of observations:
1. I believe that 60% efficiency would be the best possibility for efficiency of the boiler itself. How well are your lines insulated between the boiler and the building?
2. With no under slab or perimeter insulation, you're heating the ground as much or more than the structure. So, whatever the actual btu delivery to the slab is, you can figure a substantial portion is going into the ground, not the building. Your walls and ceiling may be well insulated, but we're talking about where the heat is going.
3. The volume of water is of little consequence compared to the mass of a 60x40'x7" slab, plus the amount of earth that your heating under it. A large buffer tank MIGHT help slightly, but the issue is still gonna be getting enough btu's into the building and I can't see your present corn boiler being able to do that in extreme cold weather when a large portion of those btu's are going into the ground.
4. Adding the Modine fan coil will help to some degree because all of the heat it's extracting from the loop will go directly into the building, but it's still gonna go out through the slab eventually - just at a slower rate.

Just my $.02 worth.